Hi, I just got the phantom 4K for the 2nd day and I'm having trouble calibrating the compass. I was trying to calibrate the compass in a condominium with high rise buildings and trees around. Could this be the case as to why I can't calibrate the compass? I've tried calibrating more than 20 times but it does not work. I get green lights, then red when I do the nose down part. Earlier today, it was raining before and after the rain stopped I brought it to the same spot to test it. It keeps saying that there is interference for GPS and I only have about 4-5 satellites. It says "safe to fly (NON-GPS)". Does the GPS signal weakens when it's cloudy? Why is this so? Should I try it in a different location? What if I have to take videos of a tall building but I am unable to calibrate compass? Any advice?